1. Field of the Invention
The invention relates generally to apparatus for gaining legitimate emergency entry into a safety deposit box or similar enclosure secured by a cam lock or similar cylinder lock. In particular, the invention relates to an apparatus capable of cutting away peripheral portions of such a lock to allow access to the secured enclosure with minimum damage to the lock.
2. Description of the Prior Art
Various circumstances require the emergency removal of locks from safety deposit boxes or other enclosures secured by cam locks or similar cylindrical locks. These unusual circumstances usually result from a loss of the key used to operate the lock. The most common practice previously employed by locksmiths charged with gaining entry to such secured enclosures results in extensive damage to and even total destruction of the lock. This conventional practice involves the drilling, tapping and subsequent pulling of the lock, this practice not only being destructive to internal elements of the lock, but also requiring a substantial amount of time to accomplish the job. Even when the lock itself is not internally drilled, conventional practices have provided for drilling one or more holes in the enclosure door in order that locking levers can be raised sequentially or drilled to defeat the lock. These alternate practices also destroy at least certain elements of the lock, require replacement of the enclosure door and are exceptionally time consuming.
The substantial amount of time required for defeating cylinder locks and the resulting damage to the locks has previously prompted efforts to improve the conventional techniques. In particular, McLaughlin, in U.S. Pat. No. 3,619,887, provides a tool intended to forceably pull a cylinder lock from a secured enclosure, the tool comprising a channel-shaped body having bevel flanges for engaging the exposed rim of the cylinder lock behind the rim, the tool being then pulled away from the enclosure by an attached implement which allows sufficient mechanical advantage to forceably pull the lock from the enclosure. Use of this prior art tool unavoidably causes damage to certain internal portions of the lock and usually damages the door of the enclosure. Further, cylinder locks which are recessed or "counter sunk" into the door of the enclosure, such as is usually the case with safety deposit box locks, cannot be pulled by such prior art tools.
The present invention finds solution to the problems thus encountered by providing apparatus capable of accurately cutting away an outer flange portion of the housing of a cylindrical lock assembly, this outer flange portion typically acting to retain the lock assembly in the door of an enclosure secured by the lock. The present apparatus allows rapid and positive location of a cutting element relative to the outer flange portion of the lock housing such that only the housing itself is damaged during the cutting operation. The present apparatus further provides structure which limits the penetration of the cutting element into the locking assembly, the cutting penetration being sufficient to cut through the outer flange, but insufficient to unnecessarily damage other portions of the locking assembly and/or the enclosure door including a structure mounting the locking assembly to the door. Use of the present invention further allows entry to be gained into the secured enclosure much more rapidly than is possible with prior apparatus, a locksmith therefore being capable of reducing job time to a substantial degree while actually causing less damage to the enclosure and the lock securing said enclosure. Replacement of parts necessary to reestablish the integrity of the lock and thus the security of the enclosure is also minimized with additional economies being thus realized.